Java tutorial
/* * #%L * ACS AEM Commons Bundle * %% * Copyright (C) 2018 Adobe * %% * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * #L% */ package com.adobe.acs.commons.json; import com.google.gson.Gson; import com.google.gson.GsonBuilder; import com.google.gson.JsonElement; import com.google.gson.JsonObject; import com.google.gson.JsonParser; import java.util.Iterator; import java.util.Map.Entry; import java.util.Optional; import java.util.Set; import java.util.function.Function; import java.util.stream.Collectors; import javax.jcr.Node; import org.apache.sling.api.resource.Resource; /** * Provide convenience methods to help use GSON JsonObjects similar to the * deprecated JSONObject in Sling Json. */ public class JsonObjectUtil { private JsonObjectUtil() { // private constructor for a utility class } public static JsonObject toJsonObject(String json) { JsonParser parse = new JsonParser(); return parse.parse(json).getAsJsonObject(); } public static JsonObject toJsonObject(Resource resource) { return toJsonObject(resource.adaptTo(Node.class)); } public static JsonObject toJsonObject(Object source) { if (source instanceof String) { return toJsonObject((String) source); } else if (source instanceof Resource) { return toJsonObject((Resource) source); } else { Gson gson = new GsonBuilder().registerTypeHierarchyAdapter(Node.class, new JcrJsonAdapter()).create(); return gson.toJsonTree(source).getAsJsonObject(); } } public static <T> JsonObject toJsonObject(T source, int depth) { JsonObject obj = toJsonObject(source); pruneToDepth(obj, depth); return obj; } public static void pruneToDepth(JsonObject obj, int depth) { AbstractJSONObjectVisitor prune = new AbstractJSONObjectVisitor() { @Override protected void visit(JsonObject jsonObject) { if (getCurrentDepth() >= depth) { Set<String> allKeys = jsonObject.entrySet().stream().map(Entry::getKey) .collect(Collectors.toSet()); allKeys.forEach(jsonObject::remove); } } }; prune.accept(obj); } public static <T> String getAsJsonString(T source, int depth) { Gson gson = new Gson(); JsonObject object = toJsonObject(source, depth); return gson.toJson(object); } public static boolean isSingularElement(JsonElement elem) { return elem.isJsonPrimitive() || (elem.isJsonArray() && elem.getAsJsonArray().size() <= 1); } public static Optional<JsonElement> getOptional(JsonObject obj, String prop) { return Optional.ofNullable(obj.get(prop)); } public static <T> T getOptionalProperty(JsonObject obj, String prop, Function<JsonElement, T> getter, T defaultValue) { return getOptional(obj, prop).filter(JsonObjectUtil::isSingularElement).map(getter).orElse(defaultValue); } public static Optional<JsonObject> getOptionalObject(JsonObject obj, String prop) { return Optional.ofNullable(obj.getAsJsonObject(prop)); } public static String getString(JsonObject obj, String prop, String defaultValue) { return getOptionalProperty(obj, prop, JsonElement::getAsString, defaultValue); } public static String getString(JsonObject obj, String prop) { return getOptionalProperty(obj, prop, JsonElement::getAsString, ""); } public static Long getLong(JsonObject obj, String prop, Long defaultValue) { return getOptionalProperty(obj, prop, JsonElement::getAsLong, defaultValue); } public static Long getLong(JsonObject obj, String prop) { return getOptionalProperty(obj, prop, JsonElement::getAsLong, null); } public static Integer getInteger(JsonObject obj, String prop, Integer defaultValue) { return getOptionalProperty(obj, prop, JsonElement::getAsInt, defaultValue); } public static Integer getInteger(JsonObject obj, String prop) { return getOptionalProperty(obj, prop, JsonElement::getAsInt, null); } public static Boolean getBoolean(JsonObject obj, String prop, Boolean defaultValue) { return getOptionalProperty(obj, prop, JsonElement::getAsBoolean, defaultValue); } public static Boolean getBoolean(JsonObject obj, String prop) { return getOptionalProperty(obj, prop, JsonElement::getAsBoolean, null); } }